923 - Pigmented Villonodular Synovitis (PVNS): An Atypical Presentation of Knee Pain

Case Diagnosis: Pigmented Villonodular Synovitis (PVNS)
 

Case Description:
We describe a case of a 38-year-old female with six months of left knee pain, instability, and swelling following an ankle inversion injury. She presented to an outside clinic with reported aspiration showing mostly blood. MRI identified a quadriceps tendon delamination tear. She improved with physical therapy but returned five months later for persistent symptoms. Second aspiration again showed mostly blood, and corticosteroid injection provided two days of relief. She subsequently presented to our clinic for a second opinion for ongoing swelling, instability, and pain worse with descending stairs. Knee examination notable for mild-to-moderate effusion and full range of motion with tenderness over the quadriceps tendon insertion. Given recurrent bloody aspirations, we obtained a repeat MRI which revealed a large effusion with lobulated hypoattenuating lesions. Findings were most consistent with pigmented villonodular synovitis (PVNS). She was referred to orthopedic surgery for further management. 



 

Discussions: PVNS is a subtype of tenosynovial giant cell tumors. It is a rare, benign joint disorder that presents with insidious joint pain, swelling, and stiffness typically in young to middle-aged adults. The knee, hip and ankle joints are most commonly affected. There are two types: localized and diffuse, characterized by the extent of joint involvement. Treatment involves surgical management, and some cases may require radiation and/or targeted drug therapies.

 

Conclusions:

For unexplained, insidious, recurrent knee symptoms, particularly when accompanied by recurrent bloody aspirations of the knee, PVNS should remain on the differential despite its rarity. It is essential to either perform direct review of external imaging, rather than relying on reports, or acquire new imaging. Timely recognition is critical to facilitate earlier intervention to maintain joint function and improve quality of life.